U.S. Pat. No. 5,421,054 to Dawson, et al., and U.S. Pat. No. 5,465,443 to Rice, et al., describe various discs for, principally, APCs. Extending upward from the upper surfaces of the discs are multiple fins. Each disc includes a central aperture whose boundary is fitted into a separate footpad, which footpad in turn is connected to a cleaner body for use.
U.S. Pat. No. 5,617,606 to Scott, II, et al., details other discs for APCs. Projecting above the majorities of the upper surfaces are one or more flutes, whose edges may be curved or straight as desired. Similarly projecting upward at boundaries of central apertures of the discs may be pins or stops. When a disc is fitted into a separate footpad, the stops may cooperate with the footpad to inhibit misorientation of the disc.
Numerous other discs have been devised whose central apertures are received by separate footpads. U.S. Pat. No. 4,351,077 to Hofmann and U.S. Pat. No. 4,949,419 to Kallenbach illustrate examples of such discs also having radial ribs. U.S. Pat. No. 4,530,125 to Hofmann illustrates another such disc also having radial slots, while U.S. Pat. No. 5,418,995 to Rice, et al., depicts such a disc additionally including radially spaced apertures adjacent its outer periphery. Yet another disc having a central aperture whose boundary is designed for receipt by a footpad is shown in U.S. Pat. No. 5,433,985 to Atkins, with this particular disc folding into a “fan shape” for transport and storage.
U.S. Pat. No. 6,122,794 to Atkins describes a component for a swimming pool cleaner identified as an integrally-molded footpad and disc. Notwithstanding the integral molding, the component continues to have a normally circular central aperture whose boundary (rim) is designed to “engage in a groove provided around the bottom of a pool cleaner body.” See Atkins, col. 2, 11. 39-40. Joining of the footpad and disc is accomplished via “a ring of thin sectioned material which provide[s] great flexibility of the disc relative to the foot.” Id., 11. 53-55 (numerals omitted).
U.S. Pat. No. 7,987,542 to Moore, et al., finally, depicts various discs at least some of which may be multi-piece. Also illustrated are footpads and an apron. Rather than having circular grooves for receiving central circular apertures of discs, some footpads may be elongated as shown in FIG. 12 of the Moore patent. The footpads may, for example, connect directly or indirectly to the apron, especially if the apron is channeled.